The present disclosure relates to a method for curing a heat-curable material in an embedded curing zone. The disclosure further relates to a method for using a curing system. The disclosure further relates to an assembly comprising a substrate and a component adhered to the substrate by means of a heat-curable material formed in an embedded curing zone between the component and the substrate.
A heat-curable material is typically cured by means of heating the material, e.g. above a curing temperature and/or during a curing period. Curing typically involves a transition such as hardening of a material, e.g. due to molecular cross-linking. The curing zone is a target area or volume wherein the heat-curable material is localized to be cured for performing its functionality, e.g. adhering surfaces together. The term “embedded” as in “embedded curing zone” may refer to an at least partial encapsulation of the curing zone, e.g. the curing zone is buried within an assembly comprising obstructions such as components and/or substrates surrounding the curing zone.
An embedded curing zone may be generally difficult to access for an external heating source such as a lamp or laser. One solution, described e.g. in US2003/0162463 or WO2006/126015, may be to provide a radiation-transparent substrate and irradiate the curing zone through the substrate. However, this is only suitable when the embedded curing zone is accessible to electromagnetic radiation. Another solution, described e.g. in JP2003218281, may be to provide an internal heating source, by burying a resistance wire next to the curing zone and selectively applying an electrical current to the wire for heating it. JP2008-085287 describes a heating circuit next to a connection member. However, this may require additional circuitry and/or the electrical current may be harmful to nearby electronic components. JP 2001-044241 describes applying heat and/or electromagnetic waves to an IC chip with a bonding layer while pressing the chip on to a circuit formed on a substrate. However, heating the IC chip may be harmful to its functioning. One solution to provide a desired curing temperature at an embedded curing zone under general circumstances may be to heat the entire assembly, e.g. by baking the assembly in an oven. However, such indiscriminate heating may be energy inefficient and/or harmful to heat-sensitive components that may be part of the assembly.
There is a desire for a more versatile method of curing a heat-curable material in an embedded curing zone.